Compounds having an N-diphenylmethyl-N'-substituted piperazine have been known as antihistamines. One compound of the class, 1-p-chlorobenzyhydryl-4-[2-(2-hydroxyethoxy)ethyl]-piperazine, has been shown to be useful in treatment of anxiety and neurotic conditions when given in dosages of 400 mg. per day. The compound has also been used for treatment of alcoholism.
Recently, patent publication WO 93-GB216 disclosed a class of diarylmethylpiperazines and piperidines which were suggested to have analgesic activity. There is no teaching of a compound of the invention wherein the substituent designated OR in this application is an alkoxy.
Calderon, et al, have discovered that certain stereoisomers of diarylmethylpiperazines are particularly effective at binding in the rat brain membranes. It was suggested that certain selected compounds of a group of diarylmethylpiperazines are useful for studying the role of the opioid receptor in drug-seeking behavior.
One of the compounds of Calderon, et al., showed evidence of 1996 fold .delta. selectivity in .mu./.delta. binding studies of opioid receptors.